What Causes Growth On My Tonsils Post Tonsillitis?

Ok a few years ago i got Tonsilites well any way i had a odd shaped formation grow on side of my tonsil and when i seen doctor i got anti biotics. I took them all but the Formation never went away. It dont hurt me but ever once in a while it gets irritant. What is this and is is dangerous?? Additonal details I have had tonsilites severel times before.